Aluminum alloy bar as well as low-temperature extrusion preparation method and application thereof

Abstract

The invention discloses an aluminum alloy bar as well as a low-temperature extrusion preparation method and application thereof, and belongs to the technical field of aluminum alloy materials. The aluminum alloy bar comprises the following components in percentage by weight: less than or equal to 0.1% of Si, 1.3%-1.4% of Fe, 2.6%-2.8% of Cu, 1.7%-1.8% of Mg, 1.4%-1.6% of Ni, less than or equal to 0.25% of Zn, 0.05% of Ti and the balance of Al. The single impurity is less than or equal to 0.05%, the total impurity is less than or equal to 0.15%, and the balance is Al. The tensile strength of the aluminum alloy bar is larger than or equal to 415 MPa, the yield strength is larger than or equal to 305 MPa, the ductility is larger than or equal to 11.0%, and grains are fine and evenly distributed.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy materials, and in particular to an aluminum alloy bar and a low-temperature extrusion preparation method and application thereof. Background Art

[0002] Heat-resistant aluminum alloys are heat-treatable and strengthened aluminum alloys, including 2A80, 2A90, etc. The heat-resistant phases and strengthening phases in the alloys make the heat-resistant aluminum alloys have sufficient oxidation resistance at high temperatures and the ability to resist plastic deformation (creep) and damage under the long-term action of temperature and load (dynamic and static). Heat-resistant aluminum alloys are widely used in aerospace and other fields due to their good thermal conductivity and light specific gravity. With the development of the national defense industry and military aviation technology, higher requirements are placed on the organization and properties of heat-resistant alloys. Therefore, the processing technology requirements for heat-resistant aluminum alloys are very strict, especially for the uniformity of grains. At present, the heat-resistant aluminum alloys produced generally have uneven cross-sectional grains, resulting in low product yields. While increasing manufacturing costs, it also seriously affects the application of the product in the aviation field.

[0003] Patent CN108193099B discloses an improved LF6 aluminum alloy and a method for eliminating the coarse grain ring in the extrusion of LF6 aluminum alloy, wherein the standard components and mass contents are: Mg 5.8% to 6.8%, Mn 0.5% to 0.8%, Ti 0.02% to 0.10%, Be 0.0001% to 0.005%, Si≤0.40%, Fe≤0.40%, Cu≤0.10%, Zn≤0.20%, and the balance is aluminum. By reasonably utilizing the range of impurity content, adding impurity content Zr and impurity content Sc and / or Er, the recrystallization temperature of the LF6 alloy is increased to achieve the purpose of eliminating coarse grains. The main purpose of this technology is to eliminate coarse grains, and the mechanical properties are not improved accordingly.

[0004] Patent CN107675034B discloses a deformed aluminum alloy for improving the coarse grain of extruded profiles, the weight percentage of each component is: Si 0.75-0.80%, Fe 0.15-0.20%, Cu 0.05-0.10%, Mn 0.28-0.30%, Mg 0.53-0.58%, Zn≤0.03%, Ti 0.01%-0.03%, Cr 0.06-0.10%, Zr 0.05-0.10%, and the balance is Al. By improving the chemical composition and regulating the content of Mg2Si, the proportion of Mg2Si increases, the shear stress increases, the migration of sliding dislocations becomes more difficult, and coarse grains are not easily produced. The patent does not improve the process, and the tensile strength of the prepared aluminum alloy is about 300MPa, the yield strength is about 290MPa, the mechanics is relatively low, and it cannot meet the requirements for the use of materials in the aviation field. Summary of the invention

[0005] The main purpose of the present invention is to provide an aluminum alloy bar and a low-temperature extrusion preparation method and application to solve the problems of coarse grain structure, uneven distribution and poor mechanical properties of aluminum alloy bars in the prior art.

[0006] In order to achieve the above object, according to one aspect of the present invention, an aluminum alloy bar is provided, comprising the following components in weight percentage:

[0007] Si≤0.1%, Fe 1.3%~1.4%, Cu 2.6%~2.8%, Mg 1.7%~1.8%, Ni 1.4%~1.6%, Zn≤0.25%, Ti 0.05%; single impurity ≤0.05%, total impurities ≤0.15%, the remainder is Al, totaling 100%.

[0008] Further, the aluminum alloy bar comprises the following components in weight percentage:

[0009] Si≤0.1%, Fe 1.35%~1.4%, Cu 2.7%~2.8%, Mg 1.75%~1.8%, Ni 1.5%~1.6%, Zn≤0.25%, Ti 0.05%; single impurity ≤0.05%, total impurity ≤0.15%, the remainder is Al, totaling 100%.

[0010] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned aluminum alloy bar by low temperature extrusion, comprising the following steps:

[0011] Step 1: Mix the ingredients according to the proportion of each component element and smelt to obtain an aluminum alloy ingot;

[0012] Step 2: performing homogenization heat treatment on the aluminum alloy ingot to obtain a homogenization heat treated ingot;

[0013] Step 3: performing heating and heat preservation treatment and hot extrusion treatment on the homogenized heat treated ingot in turn to obtain an extruded rod; wherein the heating and heat preservation temperature is 320° C. to 360° C., and the heat preservation time is 3 to 5 hours;

[0014] Step 4: performing solution heat treatment on the extruded rod to obtain a solution heat treated rod;

[0015] Step 5: The solution heat treated rod is subjected to stretching straightening and aging heat treatment in sequence to obtain an aluminum alloy rod.

[0016] Furthermore, the heating and insulation temperature is 330° C. to 360° C., and the insulation time is 3 to 5 hours.

[0017] Furthermore, the heating and insulation temperature is 335° C. to 360° C., and the insulation time is 3 to 5 hours.

[0018] Furthermore, the heating temperature of the hot extrusion die is 320°C to 340°C, and the heating temperature of the extrusion barrel is 320°C to 340°C.

[0019] Furthermore, the heating temperature of the hot extrusion die is 330°C to 340°C, and the heating temperature of the extrusion barrel is 330°C to 340°C.

[0020] Furthermore, the extrusion speed of the hot extrusion is 1.5 to 2.5 m / min.

[0021] Furthermore, the extrusion speed of the hot extrusion is 2.0 to 2.5 m / min.

[0022] Furthermore, the die structure used for hot extrusion is a flat die, the inlet angle of the die is 60° to 70°, and the working zone length is 3 to 5 mm.

[0023] Furthermore, the solution heating rate of the solution heat treatment is greater than 520°C / h.

[0024] Furthermore, the solution heating rate of the solution heat treatment is 525-800°C / h.

[0025] Furthermore, the solution heating rate of the solution heat treatment is 550-800°C / h.

[0026] Furthermore, the temperature of the solution heat treatment is 530° C. to 535° C., and the holding time of the solution heat treatment is 190 min to 260 min.

[0027] Furthermore, the aluminum alloy rod after the solution heat treatment is water-cooled to 15°C to 35°C.

[0028] Furthermore, the stretch straightening amount is ≤2%.

[0029] Furthermore, the aging heat treatment is an artificial aging heat treatment, the temperature of the artificial aging heat treatment is 175° C. to 185° C., and the time of the artificial aging heat treatment is 5 h to 8 h.

[0030] In a third aspect, the present invention provides the use of the above-mentioned aluminum alloy rod or the aluminum alloy rod obtained by the above-mentioned low-temperature extrusion preparation method in aviation materials.

[0031] The technical solution of the present invention is applied to provide a heat-resistant aluminum alloy bar and a low-temperature extrusion preparation method thereof. By optimizing the proportion of each component of the aluminum alloy, the heat treatment process, and the hot extrusion process, the deformation energy storage during the extrusion process is regulated, so that the nucleation rate and growth rate of the crystal nucleus are reduced, the grains are small and uniform, and the requirements for the use of the grains are met. The tensile strength is ≥415MPa, the yield strength is ≥305MPa, and the elongation is ≥11.0%. The low-temperature extrusion method for heat-resistant aluminum alloy extruded bars provided by the present invention is not only applicable to 2A80 and 2A90 alloys, but can also be extended to other heat-resistant aluminum alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The description, which constitutes a part of this application, is used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1 This is a low-magnification microstructure photograph of the heat-resistant aluminum alloy extruded rod prepared in Example 1 of the present invention;

[0034] Figure 2 This is a metallographic microscope image of the heat-resistant aluminum alloy extruded rod prepared in Example 1 of the present invention;

[0035] Figure 3 This is a low-magnification microstructure photograph of the heat-resistant aluminum alloy extruded rod prepared in Example 2 of the present invention;

[0036] Figure 4 This is a metallographic microscope image of the heat-resistant aluminum alloy extruded rod prepared in Example 3 of the present invention;

[0037] Figure 5 This is a low-magnification microstructure photograph of the heat-resistant aluminum alloy extruded bar prepared in Comparative Example 3 of the present invention;

[0038] Figure 6 This is a metallographic microscope image of the heat-resistant aluminum alloy extruded rod prepared in Comparative Example 3 of the present invention;

[0039] Figure 7 A schematic diagram of the inlet angle of the die used for extruding the rod of the present invention;

[0040] Figure 8 This is a schematic diagram of the process for preparing heat-resistant aluminum alloy extruded bars according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0042] Grain structure control of aluminum alloy extrusions is a technical problem in the field of aluminum processing. There are many factors that affect the uniformity and size of grains, including alloy composition, extrusion temperature, extrusion speed, solution process, etc. How to optimize the alloy composition and control various process parameters in the production process so that the microstructure and performance of heat-resistant aluminum alloy extrusion bars meet aviation needs, it is necessary to study the alloy composition and process optimization of heat-resistant aluminum alloy extrusion bars to meet user standards, improve product qualification rate, and enhance economic benefits.

[0043] According to a first aspect of the present invention, an aluminum alloy bar is provided, comprising the following components in weight percentage: Si≤0.1%, Fe 1.3%~1.4%, Cu 2.6%~2.8%, Mg 1.7%~1.8%, Ni 1.4%~1.6%, Zn≤0.25%, Ti 0.05%; individual impurities ≤0.05%, total impurities ≤0.15%, and the remainder is Al, totaling 100%.

[0044] The weight percentage of Fe, a constituent element of the aluminum alloy bar of the present invention, is selected from any value among 1.3%, 1.31%, 1.32%, 1.33%, 1.34%, 1.35%, 1.36%, 1.37%, 1.38%, 1.39%, 1.4%, or any range between two values; the weight percentage of Cu is selected from any value among 2.6%, 2.62%, 2.65%, 2.68%, 2.70%, 2.72%, 2.75%, 2.78%, 2.8%, or any range between two values. The weight proportion of Mg is selected from any value among 1.7%, 1.71%, 1.72%, 1.73%, 1.74%, 1.75%, 1.76%, 1.77%, 1.78%, 1.78%, 1.79%, 1.80% or any range between two thereof; the weight proportion of Ni is selected from any value among 1.4%, 1.42%, 1.45%, 1.48%, 1.50%, 1.52%, 1.55%, 1.58%, 1.60% or any range between two thereof.

[0045] The ingredients of the present invention include 1.3% to 1.4% Fe, 2.6% to 2.8% Cu, 1.7% to 1.8% Mg, 1.4% to 1.6% Ni, and the balance of Al as main elements. By adjusting the ratios among these elements and the proportions in the aluminum matrix, the grain refinement, uniformity, mechanical properties and heat resistance of the aluminum alloy can be improved, such as tensile strength ≥415MPa, yield strength ≥305MPa, and elongation ≥11.0%. At the same time, the above-mentioned component ratio matching designed by the present invention is suitable for low-temperature extrusion process, and the low-temperature heat treatment process can better improve the grain uniformity, refinement and other morphologies of the aluminum alloy bar, and can also save energy consumption.

[0046] As a preferred embodiment, the aluminum alloy bar of the present invention includes the following components in weight percentage: Si≤0.1%, Fe 1.35%~1.4%, Cu 2.7%~2.8%, Mg 1.75%~1.8%, Ni 1.5%~1.6%, Zn≤0.25%, Ti 0.05%; single impurity ≤0.05%, total impurity ≤0.15%, and the remainder is Al, totaling 100%.

[0047] The present invention can further improve the mechanical properties of the aluminum alloy bar by further optimizing the ratio between Fe 1.35% to 1.4%, Cu 2.7% to 2.8%, Mg 1.75% to 1.8%, and Ni 1.5% to 1.6%. The tensile strength of the aluminum alloy bar is ≥430MPa, and the yield strength is ≥320MPa.

[0048] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned aluminum alloy bar by low temperature extrusion, comprising the following steps:

[0049] Step 1: Obtain aluminum alloy ingot;

[0050] The aluminum alloy ingot is an ingot prepared by proportioning the components of the above-mentioned aluminum alloy bars, or an ingot prepared by proportioning the components of grade 2A80 or grade 2D90 aluminum alloy bars;

[0051] Step 2: performing homogenization heat treatment on the aluminum alloy ingot to obtain a homogenization heat treated ingot;

[0052] Step 3: performing heating and heat preservation treatment and hot extrusion treatment on the homogenized heat treated ingot in sequence to obtain an extruded rod; wherein the heating and heat preservation temperature is 320° C. to 360° C., and the heat preservation time is 3 to 5 hours;

[0053] Step 4: performing solution heat treatment on the extruded rod to obtain a solution heat treated rod;

[0054] Step 5: The solution heat treated rod is subjected to stretching straightening and aging heat treatment in sequence to obtain an aluminum alloy rod.

[0055] The heating and insulation temperature of the present invention is selected from any value among 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, and 360°C, or a range between any two of them; the insulation time is selected from any value among 3h, 3.5h, 4h, 4.5h, and 5h, or a range between any two of them.

[0056] In the method of the present invention, the ingot after homogenization heat treatment is firstly kept at 320°C-360°C for 3-5h, and then hot extrusion is performed. At this time, the hot extrusion temperature is about 320°C-360°C. The present invention adopts relatively low temperature heat preservation and low temperature extrusion temperature, which will cause the ingot to precipitate a fine dispersed second phase. The second phase plays a role in pinning the grain boundary and hindering the recrystallization growth during the solid solution process; it can effectively improve the uniformity of grains, improve the coarse grain phenomenon of rods, enhance the mechanical properties, and save energy consumption at the same time.

[0057] As a preferred embodiment, the present invention further optimizes the heating and insulation temperature of the homogenization heat treatment ingot to 330°C to 360°C, and the insulation time is 3 to 5 hours. The heating and insulation temperature is the same or similar to the hot extrusion temperature. The use of this insulation temperature and time is beneficial to the uniformity of the grains in the ingot in the subsequent extrusion, improves the coarse grain phenomenon, and is conducive to further improving the mechanical properties.

[0058] As a specific implementation manner, the heating temperature of the hot extrusion die is 320°C to 340°C, and the heating temperature of the extrusion barrel is 320°C to 340°C; further preferably, the heating temperature of the hot extrusion die is 330°C to 340°C, and the heating temperature of the extrusion barrel is 330°C to 340°C.

[0059] The mold temperature, extrusion barrel temperature, heating and insulation temperature, hot extrusion temperature and aluminum alloy component element ratio are adapted to each other. The aluminum alloy with a specific component ratio of the present invention is subjected to heat treatment or hot extrusion operation at the above low temperature, which can improve the coarse grain phenomenon of the aluminum alloy bar and is beneficial to the subsequent solid solution process.

[0060] As a specific implementation, the extrusion speed in the hot extrusion process is 1.5 to 2.5 m / min, preferably 2.0 to 2.5 m / min. The present invention can improve the uniformity of the grains of the aluminum alloy bar by adjusting the hot extrusion temperature and the extrusion speed.

[0061] As a specific implementation method, the die structure used for hot extrusion is a flat die, the inlet angle of the die is 60° to 70°, and the working band length is 3 to 5 mm. Figure 7 The flat die structure and the specific inlet angle selected by the present invention are more conducive to the hot extrusion process of the rod; and the use of the above-mentioned inlet angle can promote the uniformity of the grains of the aluminum alloy rod, which is conducive to improving the mechanical properties.

[0062] As a specific embodiment, the solution heating rate of the solution heat treatment is greater than 520°C / h; preferably 525-800°C / h; further preferably 550-800°C / h; the temperature of the solution heat treatment is 530°C-535°C, and the holding time of the solution heat treatment is 190min-260min.

[0063] The present invention adopts the above-mentioned reasonable heating rate, which is compatible with the solution heat treatment temperature on the one hand, and can shorten the solution heat treatment time on the other hand, saving the overall process time; if the heating rate is too slow, it is not conducive to the solution heat treatment effect, and if the heating rate is too fast, it places very high requirements on the production equipment, increasing the production cost investment.

[0064] The present invention can not only regulate the grain structure and improve the grain morphology in the rod by adjusting the solid solution temperature and the holding time, but also ensure that the solute atoms are fully dissolved into the matrix to form a supersaturated solid solution, and fully precipitate the strengthening phase in the subsequent aging process, thereby helping to improve the mechanical properties of the alloy. Too high a solid solution temperature or too long a holding time can easily lead to grain growth, which is not conducive to grain refinement. Low a solid solution temperature or too short a holding time can lead to insufficient solid solution of solute atoms, which is not conducive to mechanical properties.

[0065] As a specific implementation method, the aluminum alloy bar after solution heat treatment is water-cooled to 15° C. to 35° C.; the stretching straightening amount is ≤2%.

[0066] As a specific implementation method, the aging heat treatment is an artificial aging heat treatment, the temperature of the artificial aging heat treatment is 175°C to 185°C, and the time of the artificial aging heat treatment is 5h to 8h. The present invention can better eliminate the internal stress generated by heating, extrusion and other operations in the previous heat treatment process, hot extrusion process, and solution heat treatment process by artificial aging treatment at the above temperature and time, thereby stabilizing the organization and structure of the aluminum alloy bar, and at the same time, it is conducive to the precipitation of strengthening phases and improving the mechanical properties of the bar.

[0067] The present invention also provides a more specific method for controlling grain structure of heat-resistant aluminum alloy during low-temperature extrusion, comprising:

[0068] The following components are included by weight percentage: Si≤0.1%, Fe 1.3%-1.4%, Cu 2.6%-2.8%, Mg 1.7%-1.8%, Ni 1.4%-1.6%, Zn≤0.25%, Ti 0.05%, individual impurities≤0.05%, total≤0.15%, and the rest is Al. Aluminum ingots, Mg ingots, Al-Cu and other intermediate alloys are melted to obtain aluminum alloy ingots.

[0069] The specific processing technology is:

[0070] Step 1: performing homogenization heat treatment on the prepared aluminum alloy ingot to obtain an aluminum alloy ingot after homogenization heat treatment;

[0071] Step 2: mill the aluminum alloy ingot obtained in step 1 and then perform induction heating. The heating temperature of the ingot is 320°C to 360°C. After the ingot temperature reaches the set temperature, keep it warm for 3 to 5 hours.

[0072] Step 3: The mold structure is a flat mold, the mold entrance angle is 60° to 70°, the working belt length is 3 to 5 mm, the mold is heated to 320°C to 340°C, the extrusion cylinder is heated to 320°C to 340°C, the extrusion pad is cooled by liquid nitrogen, and then the aluminum alloy ingot treated in step 2 is placed, and the extrusion speed is 1.5 to 2.5 mm / s;

[0073] Step 4: subjecting the aluminum alloy bar obtained in step 3 to solid solution heat treatment, wherein the solid solution temperature is 530°C to 535°C, the solid solution heating rate is greater than 520°C / h, the heat preservation time is 190min to 260min, and the solid solution heat treatment is followed by water cooling to room temperature;

[0074] Step 5, stretching and straightening the bar treated in step 4, with the stretching and straightening amount being ≤2.0%;

[0075] Step 6: Perform artificial aging heat treatment on the aluminum alloy bar after stretching and straightening in step 5. The artificial aging heat treatment temperature is 175° C. to 185° C., and the insulation time is 6 h to 8 h to obtain a heat-resistant aluminum alloy extruded bar.

[0076] The schematic diagram of the process for preparing heat-resistant aluminum alloy bars of the present invention is as follows Figure 8 shown.

[0077] The present invention aims at the problem of coarse grains commonly existing in heat-resistant aluminum alloy extruded bars. By optimizing the proportion of each component of the aluminum alloy, the invention is suitable for low-temperature hot extrusion process, and the deformation energy storage during the extrusion process is regulated, so that the nucleation rate and growth rate of the crystal nucleus are reduced, which significantly improves the problem of coarse grains in the bars, makes the grains small and uniform, meets the requirements for the use of grains, and improves the mechanical properties, with tensile strength ≥415MPa, yield strength ≥305MPa, and elongation ≥11.0%. The heat-resistant aluminum alloy bars produced by the method of the present invention not only have mechanical properties that meet the requirements of the aerospace field, but also have uniform cross-sectional grain structure, which reduces the material scrap rate and production cost of processing and manufacturing enterprises.

[0078] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0079] The yield strength, tensile strength and elongation of the aluminum alloy bar product of the embodiment of the present invention are tested using a universal tensile machine; the grain size evaluation refers to the standard GB / T 3246.2-2012 Macrostructure Inspection Method for Deformed Aluminum and Aluminum Alloy Products.

[0080] Example 1

[0081] An aluminum alloy extruded bar material, wherein the proportions of its components are as follows: by weight percentage, Si 0.05%, Fe 1.3%, Cu 2.6%, Mg 1.7%, Ti 0.05%, Ni 1.4%, Zn 0.25%, a single impurity ≤ 0.05%, a total impurity ≤ 0.15%, the remainder being Al, and the total is 100%.

[0082] The raw materials Al ingot, Mg ingot, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Ni master alloy, Al-Zn master alloy, etc. are melted according to the element ratio and cast to obtain the required ingot.

[0083] The ingot is subjected to homogenization heat treatment (homogenization heat treatment temperature is 520°C, homogenization heat treatment holding time is 24h) and then hot extrusion is carried out. The extrusion die structure is a flat die, the die inlet angle is 60°, the working belt length is 3mm, and the extrusion process is as follows: the ingot temperature is heated to 320°C, and then kept warm for 3h. The extrusion barrel temperature is 320°C, the extrusion die temperature is 320°C, the extrusion pad is cooled by liquid nitrogen, and the extrusion speed is 1.5mm / s to obtain extruded rods.

[0084] The obtained extruded rods were subjected to solution heat treatment, with a solution temperature of 530°C, a solution heating rate of 550°C / h, a holding time of 190 min, and cooled to room temperature. The cooling medium was room temperature water. The rods after solution heat treatment were stretched and straightened, and the stretching straightening amount was ≤2.0%. The straightened extruded rods were subjected to artificial aging heat treatment, with an artificial aging temperature of 175°C, a holding time of 5 h, and cooled to room temperature. The cooling medium was air to obtain heat-resistant aluminum alloy extruded rods. The obtained extruded rod microstructure properties are shown in Table 1, and the low-magnification microstructure photos are shown in Table 1. Figure 1 As shown in the metallographic microstructure Figure 2 shown.

[0085] Example 2

[0086] An aluminum alloy extruded bar material, wherein the proportions of its components are as follows: by weight percentage, Si 0.05%, Fe 1.35%, Cu 2.7%, Mg 1.75%, Ti 0.05%, Ni 1.5%, Zn 0.25%, a single impurity ≤ 0.05%, a total impurity ≤ 0.15%, the remainder being Al, and the total is 100%.

[0087] The raw materials Al ingot, Mg ingot, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Ni master alloy, Al-Zn master alloy, etc. are melted according to the element ratio and cast to obtain the required ingot.

[0088] The ingot is subjected to homogenization heat treatment (homogenization heat treatment temperature is 520°C, homogenization heat treatment holding time is 24h) and then extruded. The extrusion die structure is a flat die, the die inlet angle is 65°, the working belt length is 4mm, and the extrusion process is as follows: the ingot temperature is heated to 340°C, and then kept warm for 4h. The extrusion barrel temperature is 330°C, the extrusion die temperature is 330°C, the extrusion pad is cooled by liquid nitrogen, and the extrusion speed is 2.0mm / s to obtain extruded rods.

[0089] The obtained extruded rods were subjected to solution heat treatment, with a solution temperature of 533°C, a solution heating rate of 600°C / h, a holding time of 220min, and cooled to room temperature. The cooling medium was room temperature water. The rods after solution heat treatment were stretched and straightened, and the stretching straightening amount was ≤2.0%. The straightened extruded rods were subjected to artificial aging heat treatment, with an artificial aging temperature of 180°C, a holding time of 6.5h, and cooled to room temperature. The cooling medium was air to obtain heat-resistant aluminum alloy extruded rods. The microstructure and properties of the obtained extruded rods are shown in Table 1. The low-magnification microstructure photos are shown in Table 1. Figure 3 shown.

[0090] Example 3

[0091] An aluminum alloy extruded bar material, wherein the proportions of its components are as follows: by weight percentage, Si 0.05%, Fe 1.4%, Cu 2.8%, Mg 1.8%, Ti 0.05%, Ni 1.6%, Zn 0.25%, a single impurity ≤ 0.05%, a total impurity ≤ 0.15%, the remainder being Al, and the total is 100%.

[0092] The raw materials Al ingot, Mg ingot, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Ni master alloy, Al-Zn master alloy, etc. are melted according to the element ratio and cast to obtain the required ingot.

[0093] The ingot is subjected to homogenization heat treatment (homogenization heat treatment temperature is 520°C, homogenization heat treatment holding time is 24h) and then extruded. The extrusion die structure is a flat die, the die inlet angle is 70°, the working belt length is 5mm, and the extrusion process is as follows: the ingot temperature is heated to 360°C, and then kept warm for 5h. The extrusion barrel temperature is 340°C, the extrusion die temperature is 340°C, the extrusion pad is cooled by liquid nitrogen, and the extrusion speed is 2.5mm / s to obtain extruded rods.

[0094] The obtained extruded rods were subjected to solution heat treatment, with a solution temperature of 535°C, a solution heating rate of 800°C / h, a holding time of 260min, and cooled to room temperature, with room temperature water as the cooling medium; the rods after solution heat treatment were stretched and straightened, with a stretching straightening amount of ≤2.0%; the straightened extruded rods were subjected to artificial aging heat treatment, with an artificial aging temperature of 185°C, a holding time of 8h, and cooled to room temperature, with air as the cooling medium, to obtain heat-resistant aluminum alloy extruded rods. The obtained extruded rods have organizational properties shown in Table 1; the metallographic microstructure is shown in Figure 4 shown.

[0095] Example 4

[0096] An aluminum alloy extruded bar material, wherein the proportions of its components are as follows: by weight percentage, Si 0.05%, Fe 1.4%, Cu 2.6%, Mg 1.7%, Ti 0.05%, Ni 1.4%, Zn 0.25%, a single impurity ≤ 0.05%, a total impurity ≤ 0.15%, the remainder being Al, and the total is 100%.

[0097] The raw materials Al ingot, Mg ingot, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Ni master alloy, Al-Zn master alloy, etc. are melted according to the element ratio and cast to obtain the required ingot.

[0098] The ingot is subjected to homogenization heat treatment (homogenization heat treatment temperature is 520°C, homogenization heat treatment holding time is 24h) and then extruded. The extrusion die structure is a flat die, the die inlet angle is 70°, the working belt length is 5mm, and the extrusion process is as follows: the ingot temperature is heated to 360°C, and then kept warm for 5h. The extrusion barrel temperature is 340°C, the extrusion die temperature is 340°C, the extrusion pad is cooled by liquid nitrogen, and the extrusion speed is 2.5mm / s to obtain extruded rods.

[0099] The obtained extruded rods were subjected to solution heat treatment, with a solution temperature of 535°C, a solution heating rate of 525°C / h, a holding time of 260min, and cooled to room temperature, with room temperature water as the cooling medium; the rods after solution heat treatment were stretched and straightened, with a stretching straightening amount of ≤2.0%; the straightened extruded rods were subjected to artificial aging heat treatment, with an artificial aging temperature of 185°C, a holding time of 8h, and cooled to room temperature, with air as the cooling medium, to obtain heat-resistant aluminum alloy extruded rods. The microstructure and properties of the obtained extruded rods are shown in Table 1.

[0100] Example 5

[0101] An aluminum alloy extruded bar material, wherein the proportions of its components are as follows: by weight percentage, Si 0.05%, Fe 1.3%, Cu 2.8%, Mg 1.8%, Ti 0.05%, Ni 1.4%, Zn 0.25%, a single impurity ≤ 0.05%, a total impurity ≤ 0.15%, the remainder being Al, and the total is 100%.

[0102] The raw materials Al ingot, Mg ingot, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Ni master alloy, Al-Zn master alloy, etc. are melted according to the element ratio and cast to obtain the required ingot.

[0103] The ingot is subjected to homogenization heat treatment (homogenization heat treatment temperature is 520°C, homogenization heat treatment holding time is 24h) and then extruded. The extrusion die structure is a flat die, the die inlet angle is 60°, the working belt length is 3mm, and the extrusion process is as follows: the ingot temperature is heated to 320°C, and then kept warm for 3h. The extrusion barrel temperature is 320°C, the extrusion die temperature is 320°C, the extrusion pad is cooled by liquid nitrogen, and the extrusion speed is 1.5mm / s to obtain extruded rods.

[0104] The obtained extruded rods were subjected to solution heat treatment, with a solution temperature of 530°C, a solution heating rate of 530°C / h, a holding time of 220min, and cooled to room temperature, with room temperature water as the cooling medium; the rods after solution heat treatment were stretched and straightened, with a stretching straightening amount of ≤2.0%; the straightened extruded rods were subjected to artificial aging heat treatment, with an artificial aging temperature of 175°C, a holding time of 5h, and cooled to room temperature, with air as the cooling medium, to obtain heat-resistant aluminum alloy extruded rods. The microstructure and properties of the obtained extruded rods are shown in Table 1.

[0105] Example 6

[0106] An aluminum alloy extruded bar material, wherein the proportions of its components are as follows: by weight percentage, Si 0.05%, Fe 1.35%, Cu 2.7%, Mg 1.75%, Ti 0.05%, Ni 1.5%, Zn 0.25%, a single impurity ≤ 0.05%, a total impurity ≤ 0.15%, the remainder being Al, and the total is 100%.

[0107] The raw materials Al ingot, Mg ingot, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Ni master alloy, Al-Zn master alloy, etc. are melted according to the element ratio and cast to obtain the required ingot.

[0108] The ingot is subjected to homogenization heat treatment (homogenization heat treatment temperature is 520°C, homogenization heat treatment holding time is 24h) and then extruded. The extrusion die structure is a flat die, the die inlet angle is 60°, the working belt length is 5mm, and the extrusion process is as follows: the ingot temperature is heated to 340°C, and then kept warm for 4h. The extrusion barrel temperature is 340°C, the extrusion die temperature is 340°C, the extrusion pad is cooled by liquid nitrogen, and the extrusion speed is 2.0mm / s to obtain extruded rods.

[0109] The obtained extruded rods were subjected to solution heat treatment, with a solution temperature of 535°C, a solution heating rate of 540°C / h, a holding time of 260 min, and cooled to room temperature, with room temperature water as the cooling medium; the rods after solution heat treatment were stretched and straightened, with a stretching straightening amount of ≤2.0%; the straightened extruded rods were subjected to artificial aging heat treatment, with an artificial aging temperature of 185°C, a holding time of 6.5 h, and cooled to room temperature, with air as the cooling medium, to obtain heat-resistant aluminum alloy extruded rods. The microstructure and properties of the obtained extruded rods are shown in Table 1.

[0110] Example 7

[0111] The difference between Example 7 and Example 6 is that the inlet angle of the extrusion die is 50°, the working belt length is 6 mm, and the extrusion speed is 1.2 mm / s; other operations are the same.

[0112] Example 8

[0113] The difference between Example 8 and Example 6 is that the inlet angle of the extrusion die is 80°, the working belt length is 5 mm, and the extrusion speed is 3.5 mm / s; other operations are the same.

[0114] Example 9

[0115] The difference between Example 9 and Example 6 is that the solution temperature is 520° C., the solution heating rate is 510° C. / h, and the holding time is 280 min; other operations are the same.

[0116] Example 10

[0117] The difference between Example 10 and Example 6 is that the solution temperature is 545° C., the solution heating rate is 540° C. / h, and the holding time is 175 min; other operations are the same.

[0118] Embodiment 11

[0119] The difference between Example 11 and Example 6 is that the artificial aging temperature is 165° C. and the holding time is 9 h; other operations are the same.

[0120] Example 12

[0121] The difference between Example 12 and Example 6 is that the artificial aging temperature is 195° C. and the holding time is 4 h; other operations are the same.

[0122] Comparative Example 1

[0123] An aluminum alloy extruded bar material, wherein the proportions of its components are as follows: by weight percentage, Si 0.05%, Fe 1.35%, Cu 2.2%, Mg 1.1%, Ti 0.05%, Ni 1.4%, Zn 0.25%, a single impurity ≤ 0.05%, a total impurity ≤ 0.15%, the remainder being Al, and the total is 100%.

[0124] The raw materials Al ingot, Mg ingot, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Ni master alloy, Al-Zn master alloy, etc. are melted according to the element ratio and cast to obtain the required ingot.

[0125] The ingot is subjected to homogenization heat treatment (homogenization heat treatment temperature is 520°C, and homogenization heat treatment holding time is 24h) and then extruded. The extrusion die structure is a flat die, the die inlet angle is 85°, the working belt length is 6mm, and the extrusion process is as follows: the ingot temperature is heated to 400°C, and then kept warm for 4h. The extrusion barrel temperature is 380°C, the extrusion die temperature is 380°C, the extrusion pad is cooled by liquid nitrogen, and the extrusion speed is 3.5mm / s to obtain extruded rods.

[0126] The obtained extruded rods were subjected to solution heat treatment, with a solution temperature of 530°C, a solution heating rate of 400°C / h, a holding time of 190min, and cooled to room temperature, with room temperature water as the cooling medium; the rods after solution heat treatment were stretched and straightened, with a stretching straightening amount of ≤2.0%; the straightened extruded rods were subjected to artificial aging heat treatment, with an artificial aging temperature of 175°C, a holding time of 5h, and cooled to room temperature, with air as the cooling medium, to obtain heat-resistant aluminum alloy extruded rods. The microstructure and properties of the obtained extruded rods are shown in Table 1.

[0127] Comparative Example 2

[0128] An aluminum alloy extruded bar material, wherein the proportions of its components are as follows: by weight percentage, Si 0.05%, Fe 1.4%, Cu 2.8%, Mg 1.75%, Ti 0.05%, Ni 1.6%, Zn 0.25%, a single impurity ≤ 0.05%, a total impurity ≤ 0.15%, the remainder being Al, and the total is 100%.

[0129] The raw materials Al ingot, Mg ingot, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Ni master alloy, Al-Zn master alloy, etc. are melted according to the element ratio and cast to obtain the required ingot.

[0130] The ingot is subjected to homogenization heat treatment (homogenization heat treatment temperature is 520°C, homogenization heat treatment insulation time is 24h) and then extruded. The extrusion die structure is a flat die, the die inlet angle is 50°, the working belt length is 2mm, and the extrusion process is as follows: the ingot temperature is heated to 300°C, and no insulation is performed after reaching temperature. The extrusion barrel temperature is 300°C, the extrusion die temperature is 300°C, the extrusion pad is cooled by liquid nitrogen, and the extrusion speed is 1.0mm / s to obtain extruded rods.

[0131] The obtained extruded rods were subjected to solution heat treatment, with a solution temperature of 520°C, a solution heating rate of 450°C / h, a holding time of 100 min, and cooled to room temperature, with room temperature water as the cooling medium; the rods after solution heat treatment were stretched and straightened, with a stretching straightening amount of ≤2.0%; the straightened extruded rods were subjected to artificial aging heat treatment, with an artificial aging temperature of 160°C, a holding time of 3 h, and cooled to room temperature, with air as the cooling medium, to obtain heat-resistant aluminum alloy extruded rods. The microstructure and properties of the obtained extruded rods are shown in Table 1.

[0132] Comparative Example 3

[0133] An aluminum alloy extruded bar material, wherein the proportions of its components are as follows: by weight percentage, Si 0.05%, Fe 1.3%, Cu 2.6%, Mg 1.7%, Ti 0.05%, Ni 1.4%, Zn 0.25%, a single impurity ≤ 0.05%, a total impurity ≤ 0.15%, the remainder being Al, and the total is 100%.

[0134] The raw materials Al ingot, Mg ingot, Al-Si master alloy, Al-Fe master alloy, Al-Cu master alloy, Al-Ti master alloy, Al-Ni master alloy, Al-Zn master alloy, etc. are melted according to the element ratio and cast to obtain the required ingot.

[0135] The ingot is subjected to homogenization heat treatment (homogenization heat treatment temperature is 520°C, homogenization heat treatment holding time is 24h) and then extruded. The extrusion die structure is a flat die, the die inlet angle is 65°, the working belt length is 4mm, and the extrusion process is as follows: the ingot temperature is heated to 340°C, and then kept warm for 7h. The extrusion barrel temperature is 330°C, the extrusion die temperature is 330°C, and the extrusion speed is 2.0mm / s to obtain extruded rods.

[0136] The obtained extruded rods were subjected to solution heat treatment, with a solution temperature of 533°C, a solution heating rate of 300°C / h, a holding time of 220min, and cooled to room temperature. The cooling medium was room temperature water. The rods after solution heat treatment were stretched and straightened, and the stretching straightening amount was ≤2.0%. The straightened extruded rods were subjected to artificial aging heat treatment, with an artificial aging temperature of 180°C, a holding time of 6.5h, and cooled to room temperature. The cooling medium was air to obtain heat-resistant aluminum alloy extruded rods. The microstructure and properties of the obtained extruded rods are shown in Table 1. The low-magnification microstructure photos are shown in Table 1. Figure 5 As shown in the metallographic microstructure Figure 6 shown.

[0137] Comparative Example 4

[0138] The difference between Comparative Example 4 and Example 3 is that the extrusion process is as follows: the ingot temperature is heated to 380°C, and then kept warm for 2 hours, the extrusion barrel temperature is 340°C, and the extrusion die temperature is 340°C; other operations are the same.

[0139] Comparative Example 5

[0140] The difference between Comparative Example 5 and Example 3 is that the extrusion process is as follows: the ingot temperature is heated to 300°C, and then kept warm for 6 hours, the extrusion barrel temperature is 340°C, and the extrusion die temperature is 340°C; other operations are the same.

[0141] Table 1 Microstructure and properties of extruded rods obtained in Examples 1 to 12 and Comparative Examples 1 to 5

[0142]

[0143]

[0144] The low temperature preparation method of embodiments 1 to 12 of the present invention ( Figure 7 Extrusion conditions and Figure 8 The tensile strength of the heat-resistant aluminum alloy bar obtained by heat treatment process is ≥415MPa, the yield strength is ≥305MPa, and the elongation is ≥11.0%; the grains are fine and evenly distributed, and the grain size is above 1.5 level; the low-magnification optical photos and high-magnification metallographic pictures of the aluminum alloy bar are as follows Figure 1 to Figure 4 ; Figure 1 and Figure 3 The grains of the medium bar are small and evenly distributed. Figure 2 and Figure 4 The grains in the center, 1 / 2 radius and edge of the middle bar are fine and evenly distributed.

[0145] The tensile strength and yield strength of the aluminum alloy bar prepared in Comparative Example 1 are significantly lower than those of the present invention, the grains are coarse and unevenly distributed, and the grain structure morphology of the aluminum alloy bar is poor; this indicates that the unreasonable design of the Cu and Mg contents in the aluminum alloy components leads to insufficient precipitation of the strengthening phase and low strength. The hot extrusion temperature of the ingot is too high, and the dispersed phase that inhibits recrystallization does not precipitate sufficiently, which seriously affects the grain morphology of the aluminum alloy bar.

[0146] The tensile strength, yield strength and elongation of the aluminum alloy rod prepared in Comparative Example 2 are similar to those of the present invention, but although the grain structure of the aluminum alloy rod can also be fine, its uniformity is poor; this indicates that the mismatch between the extrusion temperature and the die structure leads to uneven deformation energy storage at various positions of the extruded rod and uneven grain growth during the solid solution process.

[0147] The tensile strength, yield strength and elongation of the aluminum alloy bar prepared in Comparative Example 3 are similar to those of the present invention, but the grain structure of the aluminum alloy bar is uniformly distributed but the grains are coarse. Figure 5 and Figure 6 The grains are obviously coarse, and the surface of the aluminum alloy bar is obviously uneven and not smooth; Figure 6 The core, edge and center of the aluminum alloy bar show that the grain size is coarse, which indicates that the extrusion temperature holding time is too long, the dispersed precipitate phase grows, and the recrystallization cannot be effectively inhibited during the solid solution process.

[0148] The preparation processes of Comparative Examples 4 and 5 are different from those of the present invention only in the hot extrusion temperature of the ingots. However, due to the excessively high or low holding temperature or hot extrusion temperature, the dispersed phase cannot be effectively precipitated, and the recrystallization cannot be effectively suppressed during the solid solution process, which affects the grain refinement, uniformity and mechanical properties of the aluminum alloy rod. This shows that selecting a suitable component ratio and a matching extrusion process has a significant effect on the grain morphology and mechanical properties of the aluminum alloy rod.

[0149] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0150] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An aluminum alloy bar, characterized in that: The aluminum alloy bar comprises the following components in weight percentage: Si≤0.1%, Fe 1.3%~1.4%, Cu 2.6%~2.8%, Mg 1.7%~1.8%, Ni 1.4%~1.6%, Zn≤0.25%, Ti 0.05%; single impurity ≤0.05%, total impurities ≤0.15%, the remainder is Al, totaling 100%.

2. The aluminum alloy bar according to claim 1, characterized in that: The aluminum alloy bar comprises the following components in weight percentage: Si≤0.1%, Fe 1.35%~1.4%, Cu 2.7%~2.8%, Mg 1.75%~1.8%, Ni 1.5%~1.6%, Zn≤0.25%, Ti 0.05%; single impurity ≤0.05%, total impurity ≤0.15%, the remainder is Al, totaling 100%.

3. The low temperature extrusion preparation method of the aluminum alloy bar according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: Step 1: Mix the ingredients according to the proportion of each component element and smelt to obtain an aluminum alloy ingot; Step 2: performing homogenization heat treatment on the aluminum alloy ingot to obtain a homogenization heat treated ingot; Step 3: sequentially performing heating and heat preservation treatment and hot extrusion treatment on the homogenized heat treated ingot to obtain an extruded rod; wherein the heating and heat preservation temperature is 320° C. to 360° C., and the heat preservation time is 3 to 5 hours; Step 4: performing solution heat treatment on the extruded rod to obtain a solution heat treated rod; Step 5: sequentially performing stretching straightening and aging heat treatment on the solution heat treated rod to obtain the aluminum alloy rod.

4. The low temperature extrusion preparation method of aluminum alloy bar according to claim 3, characterized in that: The temperature of the heating and heat preservation is 330° C. to 360° C., and the heat preservation time is 3 to 5 hours; preferably, the temperature of the heating and heat preservation is 335° C. to 360° C., and the heat preservation time is 3 to 5 hours.

5. The low temperature extrusion preparation method of aluminum alloy bar according to claim 3 or 4, characterized in that: The heating temperature of the die used in the hot extrusion is 320°C to 340°C, and the heating temperature of the extrusion barrel is 320°C to 340°C; Preferably, the heating temperature of the mold is 330°C to 340°C, and the heating temperature of the extrusion barrel is 330°C to 340°C.

6. The low temperature extrusion preparation method of an aluminum alloy bar according to any one of claims 3 to 5, characterized in that: The extrusion speed of the hot extrusion is 1.5 to 2.5 m / min, preferably 2.0 to 2.5 m / min.

7. The low temperature extrusion preparation method of an aluminum alloy bar according to any one of claims 3 to 6, characterized in that: The die structure used for the hot extrusion is a flat die, the inlet angle of the die is 60° to 70°, and the working zone length is 3 to 5 mm.

8. The low temperature extrusion preparation method of an aluminum alloy bar according to any one of claims 3 to 7, characterized in that: The solution heating rate of the solution heat treatment is >520°C / h; preferably 525-800°C / h; more preferably 550-800°C / h; And / or, the temperature of the solution heat treatment is 530°C to 535°C, and the holding time is 190min to 260min; And / or, the aluminum alloy bar after the solution heat treatment is water-cooled to 15°C to 35°C.

9. The low temperature extrusion preparation method of an aluminum alloy bar according to any one of claims 3 to 8, characterized in that: The straightening amount of the stretch straightening is ≤2%; And / or, the aging heat treatment is an artificial aging heat treatment, the temperature of the artificial aging heat treatment is 175° C. to 185° C., and the time of the artificial aging heat treatment is 5 h to 8 h.

10. Use of the aluminum alloy bar according to claim 1 or 2 or the aluminum alloy bar obtained by the low temperature extrusion preparation method according to any one of claims 3 to 9 in aviation materials.

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